1. Field of the Invention
The present invention relates to a lens driving device used in a camera such as a portable phone, and in particular to a lens driving device with image stabilizer function.
2. Description of Related Art
Many cameras on sale have an image stabilizer function. An object is focused by moving a lens disposed in the camera forwards or backwards relative to the object to be shot, and meanwhile the lens is swung in a direction perpendicular to the shooting direction of the lens, thus blur flow of the image imaged on an image sensor is inhibited. For example, Japan patent application JP 2011-65140 discloses a lens driving device for auto focus which is suspended supported in the Z direction, the lens driving device can swing in X direction and Y direction relative to a base.
As shown in FIGS. 21A and 21B, in the lens driving device 600 with image stabilizer function, a structure for enabling the lens driving device 601 for auto focus to swing in the X direction and the Y direction is adopted. The lens driving device 601 includes a lens support 602 for retaining the lens 614 with an optical axis in the Z direction, a focusing coil 603 wound around the Z direction and disposed on the lens support 602, four permanent magnets 604 which are disposed on the circumferential side of the above components and retained on a magnet support 605, an upper side plate spring 606 and a lower side plate spring 607 which extend along a direction perpendicular to the Z direction, and an upper side base plate 608 and a stopper 609 which are used for holding the upper side plate spring 606 and the lower side plate spring 607. The upper side plate spring 606 and the lower side plate spring 607 are connected with the magnet support 605 and used for suspended supporting the lens support 602.
Namely, the lens driving device 601 acting as a swing part is suspended supported by the base 610 through four suspension electric wires 611. Each suspension electric wire 611 is extending along the Z direction, one end of which is connected with the base 610, and the other end sides of which is also connected with the lens driving device 601. Thus the lens driving device for auto focus is suspended supported and may swing towards the X direction and the Y direction. Moreover, coils 612a and 612b for image stabilizing wound in the X axis and the Y axis are disposed on the inner wall of the side face of a shielding cover 613, and the coils for image stabilizing are oppositely disposed with each other and spaced at an interval by taking an outer magnetic pole face of the permanent magnet 604 as reference. When the coils 612a and 612b are electrified, the Lorentz force in the Y direction and the X direction is generated in the coils 612a and 612b for image stabilizing. Reacting force corresponding to the Lorentz force is generated on the permanent magnet 604 disposed in the lens driving device 601 for auto focus. Therefore, the suspended lens driving device 601 for auto focus may swing towards directions opposite to the Lorentz force.
However, the whole lens driving device 601 including the permanent magnet 604 with large mass is supported by the four suspension electric wires 611 in a suspended manner. When the posture of the camera changes by rotating the shooting direction to the horizontal direction from the vertical direction, the suspension electric wire 611 is bent and deformed through gravity action of the lens driving device 601 for auto focus as the swing part, the center of the lens 614 is biased towards the X direction or the Y direction, the center of the image formed on an unshown image sensor disposed on the base 610 is also biased towards the X direction or the Y direction, and distortion is performed on the image formed in the image sensor.
In order to prevent the problem, the following complicated control method is adopted, namely, in the lens driving device 600 with image stabilizer function, a position detecting mechanism 615 including Hall elements is disposed on the base 610, and is used for detecting whether the lens driving device 601 for auto focus disposed on the suspension electric wire 611 in a suspended manner is biased towards the X direction and the Y direction from the center (also called off-centering) and supplying off-centering correcting current to the coils 612a and 612b for image stabilizing, so that the coils 612a and 612b for image stabilizing are respectively electrified by image stabilizing current repeatedly until the lens driving device 601 for auto focus returns to a proper central position.
Therefore, an additional part or an additional control circuit for generating the correcting current is needed to be set in the lens driving device 600, thus the lens driving device 600 is in large size, the part cost or assembling cost is increased, and the power consumption is further increased.